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H. H. JOHNSON 8; S. G. HILL. RUBBER DAM CLAMP.

No. 420,876. Patentedf'eb. 4, 1890- UNITED STATES PATENT OFFICE.

HENRY H. JOHNSON AND SYLVESTER G. HILL, OF LONDON, ENGLAND; SAID HILLASSIGNORfiO SAID JOHNSON.

RUBBER-DANI CLAMP.

SPECIFICATION forming part of Letters Patent No. 420,876, dated February4, 1890.

Application led May l1, 1889. Serial No. 310,412. (No model.)

To all whom t may concern.-

Be it known that we, HENRY I-I. JOHNSON and SYLVESTER G. HILL, citizensof the United States, residing at London, England,

I; have invented new anduseful Improvements in Rubber-Dam Clamps, ofwhich the follow'- ing is a specification. A

In illinglabial cavities in incisors, cuspids, and bicuspids, where suchcavities extend to 1o or under the gum, itis necessary tohave freeaccess to the cavity and perfect freedom from moisture, such asnaturally arises from the moisture of the salivary glands. Thesenecessities are provided for by the rubber-dam clamp for which LettersPatent No. 370,194: were issued September 20, 1887, to one of thepresent applicants; but in the former construction the clamp is made ofsheet metal, and is held in place on the tooth by the in- 2c herentelasticity of a clasp or tongue, which rendered it necessary forsecurity to tie the upper end of the device by a tape or cord passingaround the head. While such device performs the functions for whichintended, it is in a measure inconvenient and objectionable; and theobjects of the present invention are to improve the prior construction;to provide a novel rubber-dam clamp which is firmly held in correctposition by claws Without relying upon spring-pressure alone to secureit; to avoid theemployment of a tape for tying the clamp; to providesuch a construct-ion that after the clamp is placed in position it canbe adj usted to retract or raise the gum; to piovide a more rm,substantial,

and convenient device that can be fixed in position on a tooth and thegum retracted with little if any pain to the patient; to provide arubber-dam clamp that can be adjusted as occasion demands; to providemeans whereby the frame of the clamp having the Work-opening or theopening through which the dentist operates is held against movement inany direction, and to otherwise improve instruments of this type torender them more useful, efficient, and satisfactory, and lessen thediscomfort of the patient. 4 To such ends our invention consists in arubber-dam clamp combining in its structure a frame having awork-opening and adapted to retract or force the gum above the cervicalmargin of the cavity, and provided at its upper edge with a claw, an armhaving a tongue point or claw to engage the inners'urface of the tooth,and means whereby the frame and claw-arm can be drawn toward each otherto grip the tooth, and the frame and arm be adjusted one upon the -otherin the direction of the length of the tooth.

The invention also consists in the construc- 6o tion and combination ofparts hereinafter described and claimed, reference being made to theaccompanying drawings, in whiel1-,

Figure lis a view showing the position of the clamp in use with a rubberdam; Fig. 2, a central vertical section from front to rear, and Fig. 3 adetail perspective view of the clamp on an enlarged scale. I

In order to enable those skilled in the art to make and use ourinvention, we will now 47o describe the same in detail, referring to thedrawings, where the reference-numeral l indicates the frame composed ofa metal piece bent into semi-lunar form with a shank 2, havingalongitudinal slot 3, and turned down at oneend at right anglesv andprovided with a guidebearing a in the form of a sleeve l through whichloosely passes an arm 5, provided at its outer end portion with ascrewthread 6, on which is mounted a thumb-nut 8o 7. The upper edge 8 ofthe frame constitutes the gum-retractor, and is provided with aAclaw-here shown as comprising two spurs or short prongs that areadapted to bear upon thelabial surface of the tooth and constitute asteady-rest which steadies, supports, and holds the frame in correctposition. The inner end of the arm 5 is provided with a tongue point orclaw 9, preferably a bifurcated projection, lto bearupon and engage the9o inner surface of the tooth, and said arm is furnished with anattached screw-threaded stem lO, which projects up through the slot 3 inthe shank 2 of the semi-lunar frame and carries athumb-nut l2, wherebythe frame and arm can be drawn together and caused to iirmly clamp orgrip the tooth between them, as represented'in Fig. 2. The slot 3 alsopermits the frame and arm to move l lengthwise in such manner that afterthe Ioo clamp is set or fixed in position upon a tooth the semidunarframe can be moved upward to retract or raise the gum above the cervicalmargin of the cavity to be iilled. This movement of the frame isconveniently eected by screwing up the thumb-nut 7 on the screwthreadedportion of the arm 5, such nut acting against the guide-bearing orsleeve 4 of the semi-lunar frame.

The adjustment of the parts and the tixing of the clamp in position byscrews render the device more convenient, useful, and satisfactory inpractice, while it can be applied and the gum retracted gradually, sothat the patient suffers comparatively little it any pain or discomfort.Y

The frame and arm are preferablycom posed of spring metal, so that thedevice is clamped with a yielding pressure.

The rubber dam 13 is composed of a thin sheet of rubber, and is appliedas fully explained in the Letters Patentbefore alluded to, and as shownin Figs. l and i of the drawings. This dam, as usual, is provided with atape 14, or similar means, to pass around the head and support the damin position so that the lip and gum are covered.

By careful and scientific adjustment to the anatomy of the tooth theclamp can be firmly fixed in position with comparatively no pain tothepatient, and it provides ample access through the work-opening of theframe to the tooth for filling and other operations.

Having thus described ourinvention, what we claim is l. Arubber-damclamp comprisinga frame having a work-opening, and a laterally-projeeting claw located at its top edge to bear upon the labial surface ofa tooth and form a steady-rest for the frame, an arm having a lateralclaw at its upper end, which projects toward the lateral claw on theframe to en- 4o gage the inside surface of the tooth, and devices formoving the frame on the arm and .clamping the claws on the tooth,substantially as described.

2. A rubber-dam clamp comprisinga semilunar frame having a work-opening,a longitudinal slot and a claw at its upper edge, an arm having a clawand on which the se1nilunar frame is movable, a screw for adjusting theframe on the arm, and a screw on the 5o arm extending through the slotin the frame for adjusting the arm and frame toward each other to grip atooth between the claws, substantially as described.

3. A rubber-dam clamp comprising an arm having a claw at one end and ascrew-thread at the opposite end, a frame having a longitudinal slot, awork-opening, a claw at its upper edge, and a sleeve at its lower edge,

through which the arm loosely passes, a screw- 6o

